Sensor for detection of analytes

A capacitive sensor for the detection of an analyte in a fluid comprising:

• two or more sensing electrodes having a first and a second portion;
• the first portion of the sensing electrodes continuously covered with an insulator, the second portion of the sensing electrodes including an uninsulated electrode detection surface having a polydopamine semiconductive layer adhered to the electrode detection surface, wherein the second portion of the sensing electrodes is an exposed portion of the electrodes that define the electrode detection surface;
• and a receptor chemically functionalized to the polydopamine semiconductive layer of the electrode detection surface of the sensing electrodes, the polydopamine semiconductive layer or receptor selectively binding to the analyte of interest and the analyte once bound being detectable by measuring the change of capacitance of the sensing electrode;
• two or more reference electrodes having a polydopamine layer adhered to a reference electrode detection surface;
• a sensing chamber and a sample injection system, wherein the sensing chamber includes the two or more sensing electrodes and a voltage source, wherein the sensing chamber is a fluid filled chamber where fluid including an injected sample constantly flows from the sample injection system via a pump to a waste system, the sensing chamber providing a defined volume for sensing the presence and/or quantity of the analyte in the injected sample, and wherein the sample injection system includes the pump that supplies buffer to the sensing chamber and a sample injection loop for injecting the sample into the system;
• a metal shielding, wherein the metal shielding surrounds the sensing chamber, the two or more sensing electrodes, and the two or more reference electrodes;
• and
• a detection system, wherein the detection system includes two or more separate differential amplifiers that accept electrical signals from a single sensing electrode and reference electrode each and amplify the difference in current inputs between the single sensing electrode and reference electrode, and wherein the resulting amplified current is fed back to the voltage source and recorded.